This invention relates to punch myringotomy systems and methods and more particularly to a novel otological vent tube insertion apparatus for installing a novel tube prosthesis, and a novel method of inserting a tube prosthesis in the tympanic membrane.
The installation of tubes in the tympanic membrane, which separates the middle ear passage from the outer ear passage, is a well-known remedy for treating inflammation of the middle ear or otitis media. An otitis media condition is characterized by a buildup of fluid in the middle ear passageway, causing discomfort and often adversely affecting one's hearing ability.
During treatment of otitis media, an incision is usually made through the tympanic membrane and a vent or drain in the form of a tube is inserted into the incision to permit drainage of fluid from the middle ear passage to the outer ear passage. Normally a tube is placed in each ear and generally remains in place for a predetermined time period, or until the inflammation is resolved. Removal of the tubes is usually accomplished by a relatively simple non-surgical retrieval procedure.
In many instances, otological vent tubes are formed of a resilient material such as silicone rubber or polyethylene having distal and proximal flange portions as shown in U.S. Pat. Nos. 3,645,268; 3,807,409; 3,871,380; 3,948,271; 4,168,697; and 4,650,488.
To install the tubes, a myringotomy incision is made in the tympanic membrane through which the proximal flange is inserted. In this manner the proximal and distal flange portions of the tube can be disposed on opposite sides of the tympanic membrane to maintain the tube in the incision.
Although all of the vent tubes shown in the foregoing patents permit drainage of fluid, various problems afflict many of these structures. For example, in several cases the proximal radial flanges of the known vent tubes do not have sufficient rigidity to retain the tubes in place in the tympanic membrane. The tubes thus have a tendency to slip out from their installed position. The problem of inadequate tube retention in the ear is often compounded by a forceful manner in which the vent tubes are occasionally inserted in the tympanic membranes.
The forcing of the tubes into the myringotomy incision generally causes excessive enlargement of the incision. An insecure fit of the tube in the incision can thus result, which increases the tendency of the tubes to fall from their installed position.
A further problem associated with some known vent tubes is a restricted drainage flow through the vent tube. Restricted drainage flow is often due to a provision of porous members across a central portion or passageway of the vent tube which hinders the flow of liquid material. Another source of flow restriction can be due to the configuration of the central passageway in the vent tube.
Apparatus for performing myringotomies and inserting otological vent tubes are shown, for example, in U.S. Pat. Nos. 3,530,860; 3,888,258; 3,897,786; 3,913,584; and 4,473,073.
Several of the apparatus shown in the foregoing patents include an outer sleeve and an inner axially movable shaft having a sharpened distal end portion. The sharpened distal end portion is used to puncture the tympanic membrane and can also support an otological vent tube. In many instances the otological vent tube is forced through the membrane with the shaft to puncture the membrane during insertion of the tube. However, discontinuities in the surface "envelope" of the pointed end portion of the shaft member and the puncturing portion of the otological vent tube can cause tearing and/or excessive stretching of the incision in the membrane.
As a result of such tearing and stretching of the incision, it is often difficult to obtain satisfactory positioning and retention of the otological vent tube in the tympanic membrane.
It is thus desirable to provide a punch myringotomy system which can simultaneously form an incision in the tympanic membrane and locate a tube in the incision without tearing or excessively stretching the incision during installation.